CYP3A4 rs4646437: What Your Genotype Means
The rs4646437 variant is a genetic change located within the CYP3A4 gene, which plays a critical role in how the body processes many medications. Research suggests this variant may influence enzyme activity and drug metabolism, though its clinical impact remains a subject of ongoing study.
What each genotype means
Typical CYP3A4 activity
This genotype is often considered the reference or wild-type state for this variant. Research indicates that individuals with this genotype may have different drug metabolism profiles compared to those carrying the A allele, particularly regarding the processing of certain immunosuppressants like tacrolimus. Please discuss your medication dosing and potential drug interactions with your clinician or pharmacist.
This is a common genotype found across diverse global populations.
Intermediate genotype profile
Carrying one copy of the A allele may influence how your body processes specific medications metabolized by the CYP3A4 enzyme. Some studies suggest that individuals with this genotype may exhibit different drug concentration levels compared to those with the GG genotype. Always consult with your healthcare provider or pharmacist before making changes to your medication regimen.
This genotype is observed at varying frequencies in global populations, including those of East Asian and other ancestries.
Associated with altered metabolism
Research has associated the AA genotype with potential differences in the metabolism of specific drugs, such as tacrolimus, and a possible increased risk for hypertension in certain populations. Because this variant influences enzyme activity, it may affect how your body clears certain medications. Please consult your clinician or pharmacist to determine if this information is relevant to your current treatment plan.
This genotype is less common than the GG or GA genotypes but is present in various global populations.
What is rs4646437?
The rs4646437 variant is a single nucleotide polymorphism (SNP) located in the CYP3A4 gene. In genetics, a SNP represents a variation at a single position in the DNA sequence. This specific variant is situated in an intron, which is a non-coding region of the gene. While introns do not provide instructions for building proteins directly, they can act as regulatory elements that influence how much of a protein is produced or how the gene is expressed. Because of its location, researchers have investigated whether rs4646437 affects the overall function of the CYP3A4 enzyme, which is responsible for metabolizing a vast array of clinically prescribed drugs. Understanding such variants is a key focus of pharmacogenomics, the field that studies how an individual's genetic makeup influences their response to medications.
The Role of the CYP3A4 Gene
The CYP3A4 gene provides instructions for making an enzyme called cytochrome P450 3A4. This enzyme is primarily found in the liver and the intestines and is responsible for the metabolism of approximately 50% to 60% of all clinically used drugs. By breaking down these substances, the enzyme helps the body clear medications from the system. Because CYP3A4 is involved in processing so many different drugs—including immunosuppressants, antineoplastics, and blood pressure medications—even minor changes in its expression or activity can lead to significant differences in how patients respond to treatment. Variations in this gene can potentially lead to faster or slower drug clearance, which may influence the effectiveness of a drug or the risk of experiencing side effects.
Research and Evidence Strength
The evidence linking rs4646437 to clinical outcomes is currently considered limited and sometimes inconsistent. Some studies have observed associations between this variant and altered drug metabolism or liver enzyme levels in specific patient populations. For example, research has explored its potential role in the metabolism of tacrolimus in kidney transplant recipients and its association with liver enzyme elevation during certain hepatitis C treatments. However, other studies have found no significant impact on drug clearance, and some effects have been reported to differ by sex or ancestry. Because of these mixed findings and the lack of a fully established biological mechanism, it is premature to use this variant as a definitive clinical tool. Further large-scale research is required to clarify its functional significance and determine if it should be incorporated into routine clinical biomarker panels.
What You Can and Cannot Do
It is important to understand that genetic information is only one piece of a complex puzzle regarding your health. You cannot use your rs4646437 genotype to diagnose a condition or to make independent decisions about your medication dosages. If you have received genetic testing results that include this variant, do not alter your prescribed treatment plan, as doing so could be dangerous. Instead, use this information as a starting point for a conversation with your healthcare provider or a clinical pharmacist. They are the only ones qualified to interpret how your genetic profile might interact with your specific medical history and current medications. Always consult your clinician before making any changes to your health regimen, as they can provide guidance based on established clinical guidelines and your individual needs.
How common is this variant?
The frequency of the rs4646437 variant varies significantly across different global populations. Research indicates that the minor allele frequency is variable, and genotype distributions should be interpreted within the context of an individual's specific ancestral background.
Frequently asked questions
Does my rs4646437 genotype mean I will have side effects from my medication?
Not necessarily. While some research suggests this variant may influence drug metabolism, it is not a definitive predictor of side effects. Many factors, including diet, other medications, and overall health, play a much larger role in how you respond to treatment.
Should I ask my doctor for a CYP3A4 genetic test?
Genetic testing for CYP3A4 is not currently standard practice for most medications. You should discuss your concerns about medication response with your doctor, who can determine if testing is appropriate based on your specific clinical situation.
Is rs4646437 the same as CYP3A4*22?
No, they are different genetic markers. CYP3A4*22 is a specific, well-studied functional variant, whereas rs4646437 is a separate regulatory variant that is still being investigated for its clinical relevance.
Can I change my genotype?
No, your genotype is determined at conception and cannot be changed. However, understanding your genetic predispositions can help you and your doctor make more informed decisions about your healthcare.
Sources & further reading
Educational information only, last refreshed 10/18/2026. Not medical advice — these associations describe population statistics, not individual predictions.
Curious what your genotype is for rs4646437?
Upload a raw DNA file from 23andMe, AncestryDNA, MyHeritage, or FamilyTreeDNA and see this variant — plus thousands more — interpreted in your full report.
Get my report — $29Related variants in CYP3A4
This variant is highly prevalent in populations of African and indigenous descent and is linked to increased rivaroxaban exposure and potential bleeding risk.
The CYP3A4*18 variant is significantly associated with the risk of anti-tuberculosis drug-induced hepatotoxicity, with effects modulated by pre-existing liver disease status.
Intronic CYP3A4 variant (CYP3A4*1G) associated with altered enzyme expression and clinical response to various medications including tacrolimus and statins.
This SNP is associated with the activity of the major drug-metabolizing enzyme CYP3A4.
This variant defines the CYP3A4*20 allele, which is associated with a loss of function in the metabolism of various clinically important drugs.
The defining SNP for the CYP3A4*22 allele, which leads to significantly reduced metabolism of statins and immunosuppressants.